arch/x86/realmode/init.c

   1 #include <linux/io.h>
   2 #include <linux/memblock.h>
   3
   4 #include <asm/cacheflush.h>
   5 #include <asm/pgtable.h>
   6 #include <asm/realmode.h>
   7
   8 struct real_mode_header *real_mode_header;
   9 u32 *trampoline_cr4_features;
  10
  11 void __init setup_real_mode(void)
  12 {
  13         phys_addr_t mem;
  14         u16 real_mode_seg;
  15         u32 *rel;
  16         u32 count;
  17         u32 *ptr;
  18         u16 *seg;
  19         int i;
  20         unsigned char *base;
  21         struct trampoline_header *trampoline_header;
  22         size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
  23 #ifdef CONFIG_X86_64
  24         u64 *trampoline_pgd;
  25         u64 efer;
  26 #endif
  27
  28         /* Has to be in very low memory so we can execute real-mode AP code. */
  29         mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
  30         if (!mem)
  31                 panic("Cannot allocate trampoline\n");
  32
  33         base = __va(mem);
  34         memblock_reserve(mem, size);
  35         real_mode_header = (struct real_mode_header *) base;
  36         printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
  37                base, (unsigned long long)mem, size);
  38
  39         memcpy(base, real_mode_blob, size);
  40
  41         real_mode_seg = __pa(base) >> 4;
  42         rel = (u32 *) real_mode_relocs;
  43
  44         /* 16-bit segment relocations. */
  45         count = rel[0];
  46         rel = &rel[1];
  47         for (i = 0; i < count; i++) {
  48                 seg = (u16 *) (base + rel[i]);
  49                 *seg = real_mode_seg;
  50         }
  51
  52         /* 32-bit linear relocations. */
  53         count = rel[i];
  54         rel =  &rel[i + 1];
  55         for (i = 0; i < count; i++) {
  56                 ptr = (u32 *) (base + rel[i]);
  57                 *ptr += __pa(base);
  58         }
  59
  60         /* Must be perfomed *after* relocation. */
  61         trampoline_header = (struct trampoline_header *)
  62                 __va(real_mode_header->trampoline_header);
  63
  64 #ifdef CONFIG_X86_32
  65         trampoline_header->start = __pa(startup_32_smp);
  66         trampoline_header->gdt_limit = __BOOT_DS + 7;
  67         trampoline_header->gdt_base = __pa(boot_gdt);
  68 #else
  69         /*
  70          * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR
  71          * so we need to mask it out.
  72          */
  73         rdmsrl(MSR_EFER, efer);
  74         trampoline_header->efer = efer & ~EFER_LMA;
  75
  76         trampoline_header->start = (u64) secondary_startup_64;
  77         trampoline_cr4_features = &trampoline_header->cr4;
  78         *trampoline_cr4_features = read_cr4();
  79
  80         trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
  81         trampoline_pgd[0] = __pa(level3_ident_pgt) + _KERNPG_TABLE;
  82         trampoline_pgd[511] = __pa(level3_kernel_pgt) + _KERNPG_TABLE;
  83 #endif
  84 }
  85
  86 /*
  87  * set_real_mode_permissions() gets called very early, to guarantee the
  88  * availability of low memory.  This is before the proper kernel page
  89  * tables are set up, so we cannot set page permissions in that
  90  * function.  Thus, we use an arch_initcall instead.
  91  */
  92 static int __init set_real_mode_permissions(void)
  93 {
  94         unsigned char *base = (unsigned char *) real_mode_header;
  95         size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
  96
  97         size_t ro_size =
  98                 PAGE_ALIGN(real_mode_header->ro_end) -
  99                 __pa(base);
 100
 101         size_t text_size =
 102                 PAGE_ALIGN(real_mode_header->ro_end) -
 103                 real_mode_header->text_start;
 104
 105         unsigned long text_start =
 106                 (unsigned long) __va(real_mode_header->text_start);
 107
 108         set_memory_nx((unsigned long) base, size >> PAGE_SHIFT);
 109         set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT);
 110         set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
 111
 112         return 0;
 113 }
 114
 115 arch_initcall(set_real_mode_permissions);